Android what is a drawable

drawable_example.xml

<!--
Look in android we can use drawables written on xml
Like this:
-->
 
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
    <solid android:color="@android:color/white" />
    <corners android:radius="4dp" />
    <stroke android:width="1.7dp" android:color="@color/colorAccent" />
</shape>
 
<!--That is a white rectangle with rounded corners and a green border-->